The present invention pertains to an actuator for the brake system of a motor vehicle with a pedal block with a brake pedal fixed thereon pivotably, with a brake power booster with a two-part housing and with a main brake cylinder assembly unit connected to same for the admission of hydraulic power to the individual wheel brakes of the motor vehicle.
Various designs of such an actuator have been known in the state of the art and are used, in principle, in all motor vehicles. The design of the individual components of the actuator differs here in terms of size and shape as well as additional attached parts, but there are also fundamental agreements in the individual components. Thus, the brake power booster housing is manufactured from steel sheet for reasons of strength and is flanged to the pedal block, which is usually also made of metal, during the assembly of the actuator. The main brake cylinder assembly unit, which comprises a main brake cylinder housing with inner components and a reservoir for the hydraulic brake fluid, is screwed to the front side of the brake power booster facing away from the pedal block. The main brake cylinder housing is, in general, a machined metal casting. Attached parts additionally necessary for the operation of the entire actuator, such as limit switches, actuating cables, restoring springs or mounting components, are mounted individually on the entire assembly unit.
Both the selection of the material and the design of the individual assembly units, such as the usually separate supply of parts by brake vendors and, e.g., manufacturers of the pedal mechanism, lead to great manufacturing and assembly efforts and, as a result, to high costs, and, moreover, the reduction of the depth of manufacture for individual motor vehicle assembly units, which is now often desired in the automobile industry, can also be achieved only with difficulty.
The technical object of the present invention is therefore to design an actuator for the brake system of a motor vehicle such that both the manufacturing costs and the installation dimensions can be reduced. In addition, an actuator of the type according to the present invention should make it possible to substantially reduce the depth of manufacture in order to meet the needs of the modern automobile manufacture in terms of modular design.
This object is accomplished according to the present invention by the pedal block and the brake power booster housing, which faces the pedal block, being made in one piece of plastic.
The combining of the brake power booster housing with the pedal block offers decisive advantages in several respects over the prior art. On the one hand, additionally necessary components and their mounts can be inexpensively integrated in the pedal block-brake power booster housing module in a very simple manner because of the plastic material to a much greater extent than in the sheet-metal design provided hitherto. On the whole, an extremely compact assembly unit is obtained, which can be additionally complemented by the entire brake power booster housing being designed as an injection-molded plastic part, wherein the connected main brake cylinder assembly unit is integrated with a reservoir and a piston unit in the entire injection-molded plastic part. Due to this design according to the present invention, an assembly unit is obtained which can be completely preassembled and leads to a reduction in the number of the individual parts, to lower costs and, because of the large amount of plastics used, to a substantial weight reduction. In addition, the entire assembly unit can be preassembled and tested independently from the vehicle, so that the entire actuator only needs to be fastened to the splashboard of the corresponding vehicle during the final assembly proper of the motor vehicle and the brake lines must be connected to the individual wheel brakes of the motor vehicle.
Other advantageous embodiments of the subject of the present invention appear, together with the technical teaching of the principal claim, from the features of the subclaims.
It proved to be advantageous, in particular, that a hydraulic tube for receiving the main brake cylinder pistons, which said tube is jacketed by the injection-molded plastic part, is arranged within the piston unit of the main brake cylinder assembly unit. This design embodiment ensures the reliable function of the main brake cylinder as well as a correspondingly long service life; on the other hand, the injection molding of the hydraulic tube into the injection-molded plastic part of the actuator according to the present invention means very inexpensive manufacture. Moreover, the design of the actuator according to the present invention can be made even more inexpensive if a common mounting element is provided on the pedal block for mounting both the brake pedal and an additional clutch and/or gas pedal. The individual mounts with their individual parts as well as the costs needed for the mounting of the individual pedals, which are customary in the prior art, are eliminated due to these measures.
In addition, it proved to be advantageous for the pedal block to have contactless sensors for picking up the signals of the angular position of the brake pedal and the additional clutch or gas pedal, where the signals are transmitted to downstream evaluating units of an electronic unit of the motor vehicle by a central plug-in assembly unit. The contactless (Hall) sensors operate without rebound and wear, can be set electronically and lead to a further integration of the functions of the entire actuator, and the final testing of the entire module is further simplified.
In addition, the feeling of actuation for the pivoting of the individual pedals is improved by the pedal block having one or more cams, on which a spring-loaded roller connected rigidly to the brake pedal and/or the clutch and gas pedals rolls during the pivoting of the pedals.
Moreover, the manufacture of the brake power booster housing from a plastic makes it possible to integrate supply lines for admitting vacuum or ambient pressure into the interior space of the brake power booster housing in the housing wall of the brake power booster housing. This measure leads, especially in the case of two-stage brake power boosters (tandem BPBs), to a further reduction in the assembly effort.
Two exemplary embodiments of the subject of the present invention will be explained in greater detail below on the basis of the drawings attached.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiments of the invention are illustrated.